Patent GB-973545-A (GB)
Title: Improvements in or relating to screen printing
IPC: B41F15/08
Filed: 1963-04-02
Abstract: 973,545. Screeri-stencilling apparatus. PRECISION SCREEN MACHINES Inc. April 2, 1963 [April 4, 1962], No. 13006/63. Heading B6C. In a machine for continuously screen-printing webs the screen, the web and a conveyer belt for the web are locked together and moved a predetermined distance during the printing operation whilst a squeegee, in contact with the screen, is moved in another direction. On completion of this operation the squeegee and screen are raised and moved back to their respective starting positions whilst the belt supporting the material is locked to a belt support plate rigidly secured to the frame of the machine. The automatically operated machine shown in Figs. 1 and 2 comprises a frame 11 which mounts a belt support plate 19 between the upper and lower flight of an endless conveyer belt 18. The frame also mounts a reciprocable rectangular printing carriage 21 which comprises end and side frame members 21B and 21A and carries parallel side rail pairs 26A, 27A and 26B, 27B, each rail of which is vertically movable through piston and cylinder assemblies 29 or 30 relative to the frame in order to raise or lower the screens 33 relative to the upper surface of the web supported on the upper flight of the conveyer 18. The carriage 21 also carries gripper means 24 for locking the screens to the web and belt, these means comprising flat suction boxes 24A having upper perforated surfaces adapted to contact the under surface of the upper belt flight at its longitudinal edges. A similar suction box 20A is formed along the centre region of the belt support plate 19 for locking the belt to the plate during the non- printing screen and squeegee return motions. The frame of the machine also mounts a reciprocable rectangular squeegee carriage 34 which comprises end and side frame members 34A and 34B and carries parallel rail pairs 35A, 36A and 35B, 36B which mount squeegees 38 and flood bars 39. The latter are fixed relative to their support rails 36A and 36B but the squeegees are movable vertically relative to their support rails 35A and 35B through piston and cylinder assemblies 37. The squeegee carriage 34 is reciprocated through piston and cylinder drive means 40 whilst a motor 44 drives the printing carriage 21 through chain drives 45, 49 and 50 the carriage being fixed to the upper flights of the endless chains of the drives 49 and 50. Through coupling of the drives 49 and 50 to the end roller 17 of the belt 18 and through coupling of the drive 45 to the end roller 16 of the belt 18 via drives 54, and by arranging suitable clutches 56 and 57 in association with the drives to the two end rollers, the drive to the printing carriage during its printing stroke is also positively coupled to the belt 18 to supplement the drive thereto derived from the locking action between the belt and the carriage effected by the gripper means 24. During the printing operation the screen, web and belt is moved in a direction opposite to that of the squeegee. Furthermore, towards the end of this operation the forward end of the screen is lifted from the web this uplife continuing in a gradual manner until at the end of the operation the entire screen is spaced from the web. In a modified machine each squeegee is moved transversely across its associated screen by a motor driven chain drive mounted on support members carried by the inner parallel rails of the printing carriage. The machine of the invention may incorporate any number of screens. If the web is of a porous nature, e.g. woven fabric, it may be glued to the belt. If, on the other hand, the web is non- porous suction may be used to attach the web to the belt.